Currently, there is a trend toward a ubiquitous computing environment where information is available to users at any time and at any place. This trend has been facilitated, in part, by a growing demand for wireless devices. Recently, there has been a trend in developing wireless, infrastructureless network technologies to facilitate direct communication between two wireless devices. When two or more devices directly communicate using a wireless, infrastructureless network technology, they form a type of local area network, known as an ad hoc network. Wireless devices may become part of the network when they are located within the range of a device in the network. Each device (or node) in the ad hoc network could serve as a client, host, or router. Currently, a number of wireless technologies exist for supporting ad hoc networks including Bluetooth, IrDA, and 802.11. Ad hoc networks are not limited to wireless devices and some or all of the devices in an ad hoc network may use temporary plug-in connections that allow these devices to temporarily be part of the network, such as for the duration of a communications session, and communicate via wired or wireless connections.
FIG. 5 illustrates a conventional ad hoc network 500 including a set of nodes. The network 500 may use, for example, Bluetooth®, IrDA®, or IEEE 802.11 specifications. Nodes may be mobile and can move in and out of the network 500. A node 510, for example is a node in the network 500 and a node 520 is an example of a node outside the network 500. Either of these nodes may represent mobile devices that can move in and out of the network 500.
Ad hoc networks and other networks typically rely on routing protocols in order to communicate messages from a source node to a destination node through a set of intermediary nodes. In an ad hoc network, routing is a non-trivial task as nodes can move unpredictably. This behavior causes topological changes that require robust and flexible methods to discover and maintain routes. The development of ad hoc routing protocols is motivated in part by a need to enhance the communication capabilities of current wireless technologies (e.g., Bluetooth®) by allowing a node to communicate with another node that is outside of its transmission range.
The effectiveness of routing in an ad hoc network depends on the ability to provide timely information about the topology of the network to the nodes. In an ad hoc network, significant rates of topological change are expected; consequently, the distribution of routing information can easily saturate the network. This problem is exacerbated by the limited bandwidth available on the wireless links. Therefore, a protocol selection method should minimize the exchange of information to minimize network traffic.
In response to the severe constraints imposed by ad hoc networks, several protocols have been proposed that attempt to derive near-optimal solutions for the ad hoc routing problem. Such protocols include Ad hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR), Temporally-Ordered Routing Algorithm (TORA), Landmark Routing Protocol (LANMAR), and Fisheye State Routing Protocol (FSR).
Most research in the area of ad hoc routing assumes the existence of a common routing protocol to be used by all of the nodes in the network. However, the standardization of ad hoc routing protocols is in a nascent phase and many such protocols may exist in future ad hoc networks. In fact, it is possible that many of these protocols will become standardized in the near future. If this is the case, then it is possible that ad hoc networks will be comprised of nodes that are capable of using one or more ad hoc routing protocols. For example, the node 510 may currently be using a first routing protocol, and the node 520 may currently be running a second routing protocol for a second network outside the network 500. The nodes may store multiple routing protocols for use with nodes running different protocols.
In an ad hoc network where nodes may use different ad hoc routing protocols, a common ad hoc routing protocol among the nodes in the network should be established to facilitate communication between two nodes.